PA plants – what to look for and what to do about it
AN INFORMATION PACK FOR BEEKEEPERS
April 2021 Why this pack?
Pyrrolizidine Alkaloids (PAs) are a naturally occurring toxin produced by some plants, most likely as a defence against herbivores.
As honey is a food source gathered from nature, PAs make their way into honey through bees collecting nectar and pollen from plants that produce PAs. This isn’t unique to New Zealand – plants containing PAs are found all over the world – but those plants are prevalent in New Zealand.
Whilst there’s no evidence to date that PAs in honey harm humans, in order to provide certainty for our consumers and stability for our export markets, it’s important for apiarists to reduce the levels of PA in the honey they produce.
This pack helps to identify the plants and weeds that produce PA levels and offers some practical steps to mitigate risks from PAs. We hope you’ll find it useful.
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Image credit: Jacqui Geux Identifying plant sources of PAs
The main plant sources of PAs in honey are the families Boraginaceae (all genera), Asteraceae (tribes Senecioneae and Eupatorieae) and in New Zealand the Apocynaceae (genus Parsonsia). These families all produce characteristic PA types which can be used to ‘fingerprint’ the nectar source of the honey.
3 PA fingerprints in the honey jar
There are over 600 known PAs in nature. Using them all for fingerprinting is not practical, nor is it necessary. Three main types of PAs cover all known PA producing plants in New Zealand and we can use these PA types to tidily categorise the plants, as the table below demonstrates.
PA TYPE FAMILY TRIBE/GENUS
RET/SEN Asteraceae Senecioneae
INT/LYC Boraginaceae All, except Echium
Asteraceae Eupatorieae
Apocynaceae Parsonsia
ECH Boraginaceae Echium
There is detailed information on all these PA types and the common names for plants that are associated with them (whew!), later in this pack, so keep reading.
RET/SEN = Retrorsine/Senecionine type PAs
INT/LYC = Intermedine/Lycopsamine type PAs
ECH = Echimidine type PAs 4 High risk habitats – avoid these areas for hives
Our research has identified specific habitats attractive to PA plants. Keeping your hives away from these areas might well reduce PA levels in your honey.
For RET /SEN PAs Forestry blocks felled in past 5 years Burnt, cleared or barren land
Weed infested pasture
For INT/LYC PAs Bush margins that contain Parsonsia vines Wild or commercial sites, and gardens containing borage, comfrey and other Boraginaceae and Eupatorieae
For ECH PAs Wild fields and gardens of Echium species
5 New Zealand geographical PA hotspots
Our research shows that PAs occur in honeys produced throughout New Zealand, particularly INT/LYC PAs, but some regions to date appear to have a higher prevalence in certain PA types.
These areas are:
For RET /SEN PAs Northland Coromandel Peninsula
East Cape through to Wairoa
For INT/LYC PAs Wairarapa Manawatu
For ECH PAs South Island high country Central Otago
6 The long tail of high PA honeys
Most honeys in New Zealand have low PA levels. However,
73.9% approx. 6% of honeys have PA levels above 200 ug/kg of honey. These are more likely to come from the geographical hotspots and risk habitats referred to on page 6. As an industry we want to eliminate this long and undesirable tail.
12.0% 8.2% 2.4% 1.5% 0.5% 1.2% 0.4%
0-50 50-100 100-200 200-300 300-400 400-500 500-1000 1000+
PAs ug/kg honey
7 Risk management decision tree
There has to be a flow chart in an information pack – and here it is! Use this to inform your decisions around hive placements, and keep an eye on the environment around them.
YES
Does your honey Monitor Are sites Test the honey Manage the risk come from a apiary sites free of risk Do PA levels sit Retest honey geographical YES and forage plants? NO YES within the long Do PA levels sit ‘hotspot’ and/ zone for risk tail? or higher risk plants. within the long habitat? tail?
NO YES NO NO
No further action needed
It’s unlikely that we can eliminate PAs entirely from our supply chain, but bringing levels down as low as possible is the best outcome for ourselves, our consumers and our export markets.
Next, let’s take a closer look at the PA types associated with our common plants, how to identify them, where they like to hang out, and when they flower. 8 Plants relevant to New Zealand with RET/SEN PA types
Family Genus Species Common name Rural location Urban location
Asteraceae Senecio Senecio bipinnatisectus Australian fireweed Yes Minor
Senecio skirrhodon Gravel groundsel Yes Minor
Senecio biserratus Fireweed Yes No
Jacobaea vulgaris Ragwort Yes No
Senecio vulgaris Groundsel Yes Yes
Jacobaea maritima Dusty Miller No Yes
Erechtites Erechtites hieracifolius American fireweed Yes No
Brachyglottis Brachyglottis repanda Rangiora Yes No
Roldana Roldana petasitis Velvet groundsel Yes Yes
Tussilago Tussilago farfara Coltsfoot Yes Minor
9 1. Senecio bipinnatisectus (Australian fireweed)
Description Erect, annual or short-lived perennial herb, up to 2m tall. Stems are usually hairless or with a few fine scattered hairs and bristles. Leaves are feather-like in structure, 5-20cm in length and 2-8cm in width, and usually hairless. Flower discs are greenish yellow, 2mm in diameter and 5-7mm long.
Habitat Waste places, coastal sites, pasture, forest margins and clearings. Will inhabit any disturbed ground (hence the term fireweed as it frequents land cleared by fire).
Flowering Dec – Jun, extending to Aug in some regions.
10 2. Senecio skirrhodon (Gravel groundsel)
Description Annual or short-lived perennial herb, 15-50cm tall. Stems have no hair, are much-branched above and below, and are sometimes leafless and woody toward base. Leaves are 20-60mm in length, 2-10mm in width, tapered with the narrow end attached to the stems. They are fleshy and pale to mid green in colour. Some leaves may be serrated with 2-4 incisions on each side. Flowers are bright yellow with 11-16 petals 7-15mm in length.
Habitat Coastal sites, waste places, inland mainly as a weed of railway lines, yards and ballast.
Flowering Year round.
11 3. Senecio biserratus (Fireweed)
Description Annual to short-lived subsucculent perennial herb up to 1m tall but usually much less. Stems erect and stem bases are sparsely or sometimes moderately coarse-hairy. Mid stem leaves are evenly spaced and sized, 50-150 mm long. Mid stem leaves are dark green to yellow green, elliptic to narrow-elliptic with segments 3-9 per side extending along much of length. Lower stem and upper stem are pale green to purple. All leaves are hairless or sparsely haired. Flowers are pale yellow, 3-6mm in length.
Habitat Coastal and lowland sites, in early successional habitats.
Flowering Aug - Jan.
12 4. Jacobaea vulgaris (Common ragwort)
Description Erect biennial or perennial herb, 30 to 120cm tall. Stems, green in younger plants turning purple as the plant ages, can be covered with dense, fine, long hairs in places. Basal leaves also covered in fine hairs, especially in younger plants. In older plants hairs on the leaves are less frequent, often remaining hairy only on veins of the lower surface. Leaves are segmented/toothed. Flowers are bright yellow with 11-13 petals 5-12mm in length.
Habitat Mostly waste places and pasture; also riverbeds, swamps and open forest.
Flowering Nov - Apr, extending to Jul in some regions.
13 5. Senecio vulgaris (Common groundsel)
Description Erect, annual herb, 10-50cm tall. Stems moderate to densely hairy when young, becoming hairless or sparsely hairy as the plant ages. Similar for the leaves which are toothed and elliptical, 1-10cm in length and 0.5-3cm wide. Flowers are dull yellow, 1.8-2.8mm long.
Habitat Waste places, cultivated land, gardens, riverbeds and stony sites, from coastal areas to 700m.
Flowering Jan - Dec.
14 6. Jacobaea maritima (Dusty miller)
Description Jacobaea maritima is a very white-woolly, heat and drought tolerant evergreen shrub growing to 0.5–1 m tall. The stems are stiff and woody at the base, densely branched, and covered in long, matted grey-white to white hairs. The leaves are feather-like or segmented, 5–15 cm long and 3–7 cm broad, stiff, with oblong and obtuse segments, and like the stems, covered with long, thinly to thickly matted grey-white to white hairs. The flowers are yellow, daisy-like in dense bunches 12–15 mm diameter, with central disc florets surrounded by a ring of 10–13 ray florets.
Habitat Coastal sites, locally common.
Flowering Oct - Jan.
15 7. Erechtites hieracifolium (American fireweed)
Description Erechtites hieracifolium is an aggressive, erect, annual weed that grows up to 2 m tall. It is a herbaceous plant with alternate, simple leaves, on thick, green stems. The stems have fine ridges, darker green vertical lines and sparse white hair or they can be hairless. The leaves are serrated and range from unlobed to deeply lobed, with the lobe pattern. There are coarse pointed teeth on the lobes. The blade is mostly ovate to lanceolate with lobes. The flower heads are yellow coloured florets which are followed by a cluster of small, wispy achenes. The plant often branches and grows in a clump with multiple stems.
Habitat Common in moist sites in the north of the North Island Bay of Plenty, Waikato, Coromandel Peninsula and Auckland. Benefits from fire and is often one of the earliest pioneer species of areas that have recently burned. It can handle gravely soil and some degree of dry conditions. It also grows well in urban areas and around humans.
Flowering Jan-April.
16 8. Brachyglottis repanda (Rangiora)
Description Common large shrub or sometimes small tree with very large (5-15cm) thin mottled leaves with jagged edges and white underneath. New growth covered in tawny or white fuzz. Flowers small, white or cream, clustered into large conspicuous sprays
Habitat Common in coastal, lowland and lower montane shrubland and open forest. Often a pioneer species.
Flowering Jul-Nov
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Image credit: Jacqui Geux 9. Roldana petasitis (Velvet groundsel)
Description Erect perennial shrub up to 2m tall. Large round hairy leaves (up to 20 cm). bunches of yellow daisy flowers July-November. Branches hairy.
Habitat Disturbed, open sites such as forest margins, shrublands, roadsides, quarries and wasteland. It can also be found in private gardens.
Flowering Jul-Nov
18 10. Tussilago farfara (Coltsfoot)
Description Perennial mat-forming herb <20cm tall. Large leathery leaves <20cm wide, finely-toothed margins, on long creeping rhizomes. Upper side of leaf green & smooth, underside is greyish-white with woolly hairs.
Habitat Damp areas: creek beds, stream margins, gravel. Prefers free drainage but will also tolerate heavier soil conditions.
Flowering Yellow, daisy-like flowers in early spring before leaves start to grow.
19 Plants relevant to New Zealand with INT/LYC PA types
Family Genus Species Common name Rural location Urban location
Boraginaceae Borago Borago officinalis Blue borage Commercial Yes cultivation
Symphytum sp Comfrey Yes Yes
Amsinckia calycina Yellow gromwell Yes Minor
Cynoglossum amabile Chinese forget-me-not Yes Yes
Myosotis arvensis Field forget-me-not Yes Yes
Cerinthe major Honeywort Yes Yes
Lithospermum sp
Phacelia tanacetifolia Phacelia, Commercial Yes Purple tansy cultivation
Asteraceae Ageratum Ageratum houstonianum Blue billy goat weed Minor Yes
Eupatorium Eupatorium cannabinum Hemp Agrimony Yes Yes
Apocynaceae Parsonsia Parsonsia capsularis NZ Jasmine Yes No
Parsonsia heterophylla Kaihua Yes No 20 1. Borago officinalis (Common borage)
Description Annual herb originating in Syria grows to a height of 60–100cm and is bristly or hairy all over. The leaves are alternate, simple, and 5–15cm long. The flowers are complete, perfect with five narrow, triangular-pointed petals.
Habitat Indeterminate growth habit which may lead to prolific spreading. Inhabitats roadsides and waste places. Commercial cultivation is mainly for the oilseed.
Flowering Sept to May. In milder climates, borage will bloom continuously for most of the year.
Flower colours Blue mainly but may also be white and pink.
21 2. Symphytum species (Comfrey)
Description Clumps of erect stems (30–120cm high) bearing elliptic leaves that are >25cm in length. The leaves are alternate, margins are entire, hairy, and have prominent veins, hairy on the underside and there are narrow wings that originate from the base of the leaf blades. The stems are covered in hairs.
Habitat In New Zealand, its wild habits are damp, often shady areas on roadsides, bush edges, near streams and rivers. Most Symphytum cultivars prefer full sun.
Flowering October - March.
Flower colours White or violet/purple.
22 3. Amsinckia calycina (Yellow Gromwell)
Description Annual herb. Stems up to 1 m high, branched, often with long straight and short curly hairs
Habitat Locally common in drier areas, especially on arable land. North Island: not very common yet South Island: Canterbury and Otago. It has now increased greatly, probably because of resistance to herbicides.
Flowering Sept-Nov.
23 4. Cynoglossum amabile (Chinese forget-me-not)
Description Bushy annual with hairy lance-shaped leaves and cymes of sky blue flowers appearing during summer. It can obtain a height of 60cm.
Habitat It seeds easily. Wild in Wanganui district.
Flowering Flowers maybe blue, pink or white.
24 5. Myosotis arvensis (Field forget-me-not)
Description Annual to biennial herb. Stems numerous and erect, up to c.300mm high, angled. Lower leaves sessile, to c.80 × 20mm, oblanceolate to oblong, hairy on both surfaces; hairs not hooked; apex obtuse; upper leaves similar but smaller.
Habitat A widespread weed of waste places, cultivated land, and other open, modified habitats also locally common in damp sites in tussock grassland. Altitudinal range sea level to c.1000m.
Flowering October - May.
Flower colours Blue, white.
25 6. Cerinthe major (Honeywort)
Description Cerinthe major leaves are a faintly mottled blue-green, ending in nodding blue bracks (specialised leaf associated with a flower) embracing blue-purple petals.
Habitat Found in Whanganui district, Cerinthe major is a native of the Mediterranean. Though from this warm region they do survive in zones with cooler temperatures, where winters get down to zero degrees.
Flowering November – April, extending to July in some regions.
Flower colours Purple, red, pink, yellow.
26 7. Lithospermum species
Description Stems – To +50cm tall, herbaceous, simple to branching above, multiple from taproot. Leaves – Alternate, sessile, linear- oblong to lanceolate, densely appressed pubescent on both surfaces, with prominent midrib below. Inflorescence – Single flowers from leaf axils, typically sessile.
Habitat Waste ground, disturbed sites, open fields, roadsides, railroads.
Flowering October - May.
Flower colours Violet/purple, blue, white.
27 8. Phacelia tanacetifolia (Phacelia, Purple tansy)
Description It grows erect to a maximum height near 100 centimetres. The stems and leaves are coated in stiff hairs. The leaves are mostly divided into smaller leaflets deeply and intricately cut into toothed lobes, giving them a lacy appearance. The very hairy inflorescence is a one-sided curving or coiling cyme of bell-shaped flowers in shades of blue and lavender. Each flower is just under a centimetre long and has protruding whiskery stamens.
Habitat Coastal sites, locally common. Though not a problem plant it has escaped in certain areas in New Zealand.
Flowering October - January.
Flower colours Blue, violet, purple.
28 9. Ageratum houstonianum (Blue billy goat weed)
Description A short-lived herbaceous plant with softly hairy stems and leaves.Up to 2 m tall. leaves in pairs, stalked and divided into 3 segments, each with toothed edges, flowerheads a flat mass of small blue flowers on top of each stemand lack any obvious ‘petals’.
Habitat Prefers open sunny spots along forest edges. Was introduced as an ornamental plant.
Flowering All year
Flower colours Blue
29 10. Eupatorium cannabinum (Hemp agrimony)
Description Tall upright herb with downy hairy branches up to 2 m tall, leaves in pairs, stalked and divided into 3 segments, each with toothed edges, flowerheads a flat mass of small pink flowers on top of each stem.
Habitat Wetlands and riparian margins of water bodies, particularly areas that are rich in Nitrogen. Locally well established in South Taranaki and Wanganui District.
Flowering Jan - Mar
Flower colours Red / Pink, Violet / Purple, White
30 11. Parsonsia heterophylla (NZ Jasmine)
Description Twining climber, through small trees or large shrubs, shade tolerant with an interesting juvenile stage.
Habitat Commonly found in somewhat open habitats, such as bush margins and coastal forest; although it can tolerate considerable amounts of shade in lowland forests.
Flowering January to March.
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Image credit: Jacqui Geux 12. Parsonsia capsularis (Kaihua)
Description Twining climber, through small trees or large shrubs, shade tolerant with an interesting juvenile stage.
Habitat Commonly found in somewhat open habitats, such as bush margins and coastal forest; although it can tolerate considerable amounts of shade in lowland forests.
Flowering January to March.
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Image credit: Jacqui Geux Plants relevant to New Zealand with ECH PA types
Candidate Family Subtribe Genus Common names Rural location Urban location plants in NZ
Boraginaceae Echinaceae Echium Echium vulgare Vipers bugloss Yes Minor
Echium Echiinae/ Minor Yes plantagineum Paterson’s curse/ Bluebedder
Echium Pride of Madeira Potentially Yes candicans weedy
Echium pininana Giant bugloss Potentially Yes weedy
33 1. Echium vulgare (Vipers bugloss)
Description Densely bristly annual or biennial herb to 50- 90 cm high. Deep taproot. Stems stiff, erect, covered in reddish bristly hairs, with many short branches. Basal rosette leaves to 15 x 5 cm, narrow, stiffly bristly, harsh to touch. Stem leaves much smaller, alternate, also rough. Flowers funnel-shaped, 5- petalled, 12-18 mm long, pink in bud, becoming vivid blue 4 long stamens protruding and 1 smaller inside flower.
Habitat Short tussock grassland, herbfield, bare land, riverbeds, usually in dry, low fertility inland areas.
Flowering Nov -Jan
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Image credit: Jacqui Geux 2. Echium plantagineum (Pattersons’ curse or Bluebedder)
Description Less common (warmer areas only), has flowers 2-3 cm long, purplish-blue, with 2 protruding stamens, leaves less harsh.
Habitat Short tussock grassland, herbfield, bare land, riverbeds, usually in dry, low fertility inland areas.
Flowering Dec - Feb
35 3. Echium candicans (Pride of Madeira)
Description It is a large herbaceous perennial shrub, growing to 1.5–2.5m. In the first year after germination the plant produces a broad rosette of leaves. In the second and subsequent years more or less woody flowering stalks are produced clothed in rough leaves.
Habitat Cultivated as an ornamental plant for traditional and drought tolerant water conserving gardens. It is particularly suitable for coastal planting. It is a common garden escapee onto road-side verges and shingle banks throughout the drier parts of both the North and the South Islands.
Flowering Spring through summer.
36 4. Echium pininana (Giant bugloss)
Description Shrubby herbaceous biennial or triennial (<2-4 m) growing from a deep taproot. Narrowly lance-shaped, deeply veined rosette leaves (25-50 cm), are covered in fine, rough hairs. Stem leaves are similar to rosette leaves but are narrower and shorter (10-25 cm long). Main, unbranched, cylindrical flowering stem resembles a woody trunk (1-3 m tall). Biennial or triennial, it typically remains as a tall rosette the first year, flowers the second or third year, and then dies after shedding its seed.
Habitat Prefers sunny habitats with moderately moist conditions. Thrives on steep and disturbed hillsides in coastal habitats. Limited by harsh winters and full shade.
Flowering Dec to Feb
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